Conventionally, the bumper for the racket frame, for example, such as the embodiments illustrated in FIGS. 1 to 4, comprises a flat strip a and a plurality of tubes b in one or two rows, extending perpendicularly from the inner surface of said strip a. When the bumper is attached onto the outside of the racket frame, said tubes are inserted through the stringing holes preformed in said frame from the outside to the inside thereof, in order to guide the strings of the racket readily passing through the frame.
In U.S. patent application Ser. No. 07/918,466 filed Jul. 22, 1992 by this inventor, a racket with an improved vibration absorbing construction is disclosed and characterized int hat a ridge portion is raised along inner periphery around the had, both lateral sides and the yoke of the frame at the substantial center line, and a soft cushion material is disposed over said ridge portion in direct contact with the strings passing through the frame to accomplish the vibration absorbing effect of the strings all over the strike surface within said frame. In cooperation with this construction, the strings should be obliquely passed through the frame from the outside center thereof along opposite directions alternately to opposite sides of said ridge portion, this is quite different from the conventional manner of the stringing substantially perpendicular to the cross-section of the frame. So that the conventional bumper with perpendicular tubes cannot applies herein. On the contrary, a bumper having oblique tubes along opposite directions alternately is impossibly manufactured by injection moulding process.